Curveball and Slider Pitchers and the DL

Recently, I posted my 2012 starting pitcher DL projections. In the projections, I used games started, age, and injury history to predict the percentage chance a pitcher will end up on the DL. Today, I am going to give an initial stab at how throwing a large number of curveballs and sliders affects a pitcher’s DL chances.

I started by looking at the season after the season in which a pitcher threw over 120 innings. Normally, 39% of these pitchers will end up on the DL. The percentage increases even more if the pitcher threw a large number of sliders or curveballs.

I wanted to look at extreme slider pitchers. For the cutoff, I used pitchers who threw sliders over 30% of the time. For this list, we found 43 pitcher seasons (around four pitchers per year). The list includes such names as Francisco Liriano, Hiroki Kuroda and Ervin Santana.

The list is not huge. Most starters limit the number of breaking balls they throw. On the other, of the qualified relievers in the league, around 14 pitchers per year make the 30% threshold in one of the breaking ball categories. The problem right now with looking at relievers is that we haven’t established a baseline DL percentage. For now, I will have to work with the limited number of starters. Of these pitchers, over 46% of them ended up on the DL in the next season. While that isn’t a huge jump, it does show some of the extra stress that throwing sliders puts on a pitcher’s arm. To get an idea of pitchers who threw a large number of sliders, here are the top 10 slider-throwing starting pitchers from 2011.

Rank	Name	SL%
1	Ervin Santana	38.4%
2	Bud Norris	36.2%
3	Edwin Jackson	33.7%
4	Madison Bumgarner	32.4%
5	Michael Pineda	31.5%
6	Ryan Dempster	31.1%
7	Francisco Liriano	28.8%
8	Bruce Chen	28.7%
9	Felipe Paulino	28.3%
10	Alexi Ogando	27.7%

For curveballs, I have to move the percentage minimum down even lower (to 25%) to get a decent number of pitchers. Twenty-seven pitcher seasons make that threshold, with such names as A.J. Burnett, Josh Beckett and John Lackey populating the list. Of these starter seasons, 51% of the pitchers ended up on the DL the next season. For reference, here are the top 10 curveball-throwing starters from the 2011 season:

Rank	Name	CB%
1	Wandy Rodriguez	37.2%
2	A.J. Burnett	33.1%
3	Erik Bedard	31.2%
4	Gio Gonzalez	27.8%
5	Jeff Niemann	23.7%
6	Jonathon Niese	22.9%
7	Brett Myers	22.7%
8	Ivan Nova	22.4%
9	Philip Humber	21.7%
10	James Shields	21.0%

These pitchers have some added risk for missing time in the season. The risk must be weighed with the pitcher’s quality and age to determine their value. If you are looking at two pitchers that have similar projected numbers, look to pick up the pitcher who throws fewer sliders or curveballs.